Phase II Study of the Anti-Cytotoxic T-Lymphocyte–Associated Antigen 4 Monoclonal Antibody, Tremelimumab, in Patients With Refractory Metastatic Colorectal Cancer

Safety and efficacy of tremelimumab (CP-675,206), a fully human anti-cytotoxic T-lymphocyte-associated antigen 4 (CTLA4) monoclonal antibody, were assessed in patients with treatment-refractory colorectal cancer.A single-arm, multicenter, phase II trial was conducted in patients with Eastern Cooperative Oncology Group performance status or= 180 days after enrollment. One patient (2%; 90% CI, < 1% to 10%) had a stable pelvic mass and substantial regression in an adrenal mass (partial response). This patient received five tremelimumab doses; response duration was 6 months (enrollment to disease progression, 15 months).Tremelimumab did not demonstrate clinically meaningful single-agent activity in this patient population, although the number of survivors at 6 months and the one patient with confirmed partial response are potentially interesting. Further study of tremelimumab in combination with other agents may be warranted.